Sec 500 (Most Version)

7/28/2019 Sec 500 (Most Version)

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Base and Surface Courses (Bituminous) Section 500

Base and Surface Courses (Bituminous)

500

Base and Surface Courses (Bituminous)

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Base and Surface Courses (Bituminous) Section

500

501. PREPARATION OF SURFACE

501.1 . Scope

This work shall consist of preparing an existing granular or black-topped surface

to specified lines, grades and cross-sections in advance of laying a bituminous course.The work shall be performed on such widths and lengths as shown in applicable drawing

and consist of scarifying and re-laying the granular base course and/or scarifying the

existing surface, filling of potholes, sealing of cracks and/or application of a profilecorrective course (levelling course) as necessary.

501.2. Materials

501.2.1. For scarifying and re-laying the granular surface: The materials used

shall be coarse aggregates salvaged from scarification of the existing granular base coursesupplemented by fresh coarse aggregates and screenings so that aggregates and screening

thus supplemented correspond to Clause 404: Water Bound Macadam or Clause 406: WetMix Macadam, as the case may be.

501.2.2. For patching potholes and sealing cracks: For patching potholes,

approved material having same specification as that of profile corrective course shall be

used. For sealing small cracks finer than 3 mm, a fog seal conforming to Section 3000shall be applied while larger cracks wider than 3 mm shall be treated with an emulsion

slurry seal, conforming to Clause 516.

501.2.3. For profile corrective course: A profile corrective course (levelling

course) is essentially a pavement base material course for correcting the existing

pavement profile which has either lost its shape or has to be given a new shape to meetthe requirement of specified lines, grades and cross-sections.

It shall be differentiated from the strengthening course or other type of structural

pavement course needed for upgrading as a remedial measure against inherently deficientand/or distressed pavement. It is meant to remove the irregularity in the existing road

profile only.

501.2.4. Profile corrective course and its application: The type of material for

profile corrective course shall be as shown on the drawing. If it is to be laid as part of the

overlay/strengthening course, the profile corrective course material shall be of the same

specification as that of the overlay/strengthening course. However, if provided as aseparate layer, it may be of the same specification as the layer over which it is to be laid

or intermediate between underlying layers, as shown on the Drawing.

(i) Wherever isolated high spots projecting over the pavement surface do

exist, the same shall be cut by milling machine or any other approved

method, to minimise the profile corrective course requirement. If, in the

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process, the bottom layer gets disturbed, the local area shall be cut and

filled with profile with profile corrective course material.

(ii) Where the maximum profile corrective course thickness works out to be

not more than 40 mm, it shall be done as an integral part of the overlaycourse. In other cases, the profile corrective course shall be provided as a

separate layer adopting such construction procedures and using such

equipment as may be appropriate to the specified type of material andthickness of the course to be provided.

501.3. Construction Operations

501.3.1. Preparing existing granular surface: Where the existing surface is

granular, all loose and disintegrated materials shall be removed and the surface lightlywatered if the profile corrective course to be provided as a separate layer is also granular.

If, however, over the existing granular surface, a profile corrective course of bituminousmaterial is to be laid, the existing granular surface shall be primed as per Clause 502.

501.3.2.Scarifying existing bituminous surface: Where necessary, the existing

bituminous layer in the specified width shall be removed with care without causing undue

disturbance to the underlying layer by suitable method approved by the Engineer. Afterremoving it, all loose and disintegrated materials of underlying layer which might have

been disturbed in the process of removal shall, before laying of the overlay course, be

reset properly by spreading/hand packing of aggregates and compacting with suitableroller/heavy hand rammers/approved mechanical tamper so that the level of the top

surface of such scarified area shall be even and properly graded with respect to adjoining

surface. Where applicable, the granular surface, after removal of the existing bituminouslayer, shall be primed as per Clause 502 to receive a bituminous profile corrective course.

Reusable materials shall be stacked as directed by the Engineer with all lift and lead of

1000 m.

501.3.3. Patching of potholes and sealing of cracks: Before providing profile

corrective course on the existing pavement, potholes, if any, shall be drained of water, cut

to regular shape with sides vertical upto the affected depth and slightly beyond the limitsof affected area and dried. All loose and disintegrated materials from it shall be removed.

The potholes shall then be filled with material as per Clause No.501.2.2 in layers not

exceeding 75 mm after painting the sides and bottom with a thin layer of hot straight-run

bitumen/emulsion and each layer shall be compacted with approved mechanical tampers/small vibratory roller and the top layer shall be flush with the existing bituminous

surface. All loose and/or surplus materials on the surface after making good the potholes,

shall be removed.

The cracks in the old pavement surface shall be sealed with a fog seal if cracks are

small (less than 3 mm width); fog seal consist of a spray of a bituminous cutback or aslow-setting bitumen emulsion diluted with an equal amount of water, the rate of spray

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being 0.5 to 1.0 litre/sq.m depending upon the texture and dryness of the existing

bituminous surface. The spray is allowed to set to a firm condition and traffic is allowedonly thereafter so as to ensure that the material is not picked up by traffic. For large

cracks, the sealing shall be done with emulsion slurry seal as per Clause 516 of these

Specifications.

501.3.4 Laying the profile corrective course

501.3.4.1. After preparing the granular surface as in Clauses 501 3.1 and 501.3.2,the profile corrective course with material as per Clause 501.2.3/501.2.4 shall be laid and

compacted to the requirement of particular Specification clause. Where a bituminous

profile corrective course is to be laid over a primed granular surface, a tack coatconforming to Clause 503 shall be applied prior to laying profile corrective course.

501.3.4.2. An existing bituminous surface shall be prepared as per Clause 501.3.3.and after applying a tack coat conforming to Clause 503, the bituminous profile

corrective course shall be laid and compacted to the requirement of particularSpecification clause.

501.3.5. In specific situation of short sags or depressions in the pavement, it may

become necessary to provide corrective course in the form of flat wedges. Normally,

layers in maximum thickness at any point more than 100 mm shall not be provided. Inplacing multiple lifts, the lift of shortest length (at the lowest portion of the

sag/depression) should be provided first, with successive lifts extending over and fully

covering underneath layer, precluding development of a series of joints on the topsurfaces, as illustrated in Fig. 500-1.

For camber correction or correction of superelevation of the existing carriageway,method as shown in the illustrative Fig. 500-2 shall be adopted depending on the profile

of the existing carriageway.

See diagrams on pages 142 and 143 of Specifications.

501.3.6. Covering the profile corrective course: Work of Profile CorrectiveCourse shall be so planned that it shall be covered by the designed base/wearing course at

the earliest, before opening to regular traffic.

501.4. Surface Finish and Quality Control of Work

Relevant provisions of Section 900 shall be exercised by the Engineer.

501.5. Arrangement for Traffic

During the construction operations, arrangement of traffic shall be done to Clause112.

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501.6.Measurements for Payment

501.6.1. The work of filling potholes shall be considered incidental to the

construction of Profile Corrective Course/bituminous course for which the existing

pavement surface is prepared.

The work of filling cracks by applying fog seal or emulsion slurry seal shall be

measured in square metres, and paid separately.

501.6.2. Scarifying existing bituminous surface shall be measured in square

metre.

501.6.3. Profile Corrective Course shall be measured as volume compacted in

position in cubic metres or in tonnage as specified in the contract. The volume shall beworked out by plotting the exact profile of Profile Corrective Course as built up at site

and superimposed on the existing pavement profile.

501.7. Rates

501.7.1. Contract unit rate for scarifying of existing bituminous surface including

repairing/resetting disturbed underlying layer and also removing and stacking reusable/unusable materials shall include cost of all labour, supply of materials needed for

repair/resetting, hire charges of tools and plant and transportation of scarified materials

with all lifts and upto a lead of 1000 m.

501.7.2. The contract unit rate for Profile Corrective Course shall be payment in

full for carrying out the required operations including full compensation for:

(i) Making arrangements for traffic to Clause 112;

(ii) Providing all materials to be incorporated in the work including anyroyalties, fees, rents (where applicable) and all leads and lifts, unless the

contract specifically excludes any item of material required for the work

or provides for separate payment in accordance with Clause 514;

(iii) Preparation of the exposed surface/existing surface including filling of pot

holes, all cleaning operations and application of track coat;

(iv) All labour, tools, equipment and incidentals necessary to complete the

work to the Specifications; and

(v) Carrying out the work in part widths of road where directed by the

Engineer.

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501.7.3. The contract unit rate for sealing cracks by applying fog seal shall be

inclusive of providing all materials and tools and plant and carrying out the work. Thecontract unit rate for sealing cracks by providing emulsion slurry seal shall be as set forth

in Clause 516.9.

502. PRIME COAT OVER GRANULAR BASE

502.1. Scope

This work shall consist of application of single coat of low viscosity liquid

bituminous material to an absorbent granular surface preparatory to any superimposed

bituminous treatment or construction.

502.2.1. Materials

502.2.1. The choice of a bituminous primer shall depend upon the porosity

characteristics of the surface to be primed as classified in IRC : 16. These are:

(i) Surfaces of low porosity; such as wet mix macadam andwater bound macadam,,

(ii) Surfaces of medium porosity; such ascement stabilized soil base,

(iii) Surfaces of high porosity; such as a gravelbase .

502.2.2. The different ranges of viscosity requirements for the primers to be usedfor the different types of surfaces to be primed as classified in 502.2.1, are given in Table

500-1.

TABLE 500-1. VISCOSITY REQUIREMENT AND QUANTITY OF

BITUMINOUS PRIMER

Type of surface Kinematic Viscosity of

Primer at 60o C

(Centistokes)

Quantity per

10 sq. m

(kg)

Low porosity 30-60 6 to 9

Medium porosity 70-140 9 to 12

High porosity 250-500 12 to 15

502.2.3. The bituminous primer shall be Medium Curing Cutback (MC) producedby fluxing, in an approved manner, bitumen of 80/100 penetration grade with kerosene.

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The cutback shall be free from water and shall not show any signs of separation prior to

use. Slow setting Cationic emulsion as per IS : 8887 may also be used, but the particulargrade to be used for the work shall be got approved by the Engineer.

Sampling and testing of bituminous primer shall be as per IS : 217; IS : 454 and

IS : 8887.

502.3. Weather and Seasonal Limitations

The bituminous primer shall not be applied on a wet surface or during dust storm

or when the weather is foggy, rainy or windy. The prime coat for surface treatment

should not be applied when the temperature in the shade is less than 10oC.

502.4. Construction

502.4.1. Equipment: The primer distributor shall be pneumatic tyred self-

propelled pressure distributor equipped for spraying the material uniformly at thespecified rates and temperatures. Spraying by manual methods may be allowed for small

areas at the discretion of the Engineer. Power broom and/or blowers may besupplemented by hand brooms as directed by the Engineer.

502.4.2. Preparation of road surface: The surface to be primed shall be sweptclean, free from dust and shall be dry . It shall be shaped to the specified grades and

section. It shall also be free from ruts, any other irregularities and segregated materials.

Minor depressions and potholes may be ignored until the surface is primed, after whichthey shall be patched with a suitable premix material prior to the surface treatment.

502.4.3. Application of bituminous primer: The bituminous primer shall besprayed/distributed uniformly over the dry surface, prepared as per Clause 502.4.2 using

self-propelled sprayer equipped with self-heating arrangement, suitable pump, adequate

capacity compressor and spraying bar with nozzles having constant volume or pressure

system capable of supplying primer at specified rates and temperatures so as to provide auniformly unbroken spread of primer. If the surface to be primed is so dry or dusty as to

cause freckling of bituminous material, it shall be lightly and uniformly sprinkled with

water immediately prior to priming; however, the bituminous material shall not beapplied till such time as no surface water is visible. The primer shall be applied at the rate

as specified in Table 500-1.

Temperature of application of a primer need only be high enough to permit theprimer to be effectively sprayed through the jets of the spray bar and to cover the

granular base surface uniformly in the desired quantity.

The desirable range of temperatures at the time application of MC-30, MC-70 and

MC-250 grades shall be 30 to 550 C; 50 to 80 0 C and 75 to 100 0 C respectively. For a

bituminous emulsion primer , the range of spraying temperature may be 20 to 60 0 C.

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Following the application of bituminous material, the surface shall be allowed to

cure for at least 24 hours or for any other period so as to allow penetration into the basecourse and aeration of volatiles from the primer material. If it is not absorbed within 24

hours after application, sand shall be spread over the surface to blot the excess primer.

Care shall be taken to prevent over-priming; any pools of excess primer left on any part

of the surface shall be swept out over the adjacent surface before spreading sand.

The primer coat shall be applied only on the topmost water bound macadam or any

granular layer, over which the bituminous base course/wearing course is to be laid.

502.4.4. Curing of primer and opening to traffic: It shall always be ensured that

while opening to any kind of traffic, the primed surface is fully cured and is not sticky toavoid being picked up by traffic. Normally, the primed surface shall be allowed to cure

for not less than 24 hours and during this period no traffic of any kind shall be permitted.

502.4.5. Laying of bituminous course over primed surface: Bituminous base

course or wearing course shall be laid over the primed water bound macadam, wet mixmacadam or any other granular base course, in the usual manner as per relevant

Specification for the same including the requirement of tack coat as per Clause 503.

502.5. Quality Control of Work

Control on the quality of materials and work shall be exercised by the Engineer in

accordance with Section 900.

502.6. Arrangement for Traffic

During the construction operations, arrangement of traffic shall be done as perClause 112.

502.7. Measurements for Payment

Prime coat shall be measured in terms of surface area of application in squaremetres.

502.8. Rate

The contract unit rate for prime coat shall be payment in full for carrying out the

required operations including full compensation for all components listed in Clause 401.8

(i) to (v) and as applicable to the work specified in these Specifications.

503. TACK COAT

503.1. Scope

This work shall consist of application of a single coat of low viscosity liquid

bituminous material to an existing road surface preparatory to another bituminousconstruction over it.

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503.2. Materials

Binder: The binder used for tack coat shall be a bituminous emulsion or cutback

as specified in the Contract.

503.3. Construction Operation

503.3.1. Preparation of base: The surface on which the tack coat is to be appliedshall be cleaned of dust and any extraneous material before the application of the binder,

by using a mechanical broom or any other approved equipment/method as specified by

the Engineer.

503.3.2. Application of binder: Binder may be heated to the temperature

appropriate to the grade of cutback used and approved by the Engineer and sprayed onthe base at the rate specified in Table 500-2. The normal range of spraying temperature

for a bituminous emulsion shall be 20 0 C - 60 0 C and for a cutback 50 0 C 80 0C if RC-70/MC-70 grade is used. It shall be the responsibility of the Contractor to carefully

handle the inflammable bituminous cutback material so as to safeguard against any firemishap. The binder shall be applied uniformly with the aid of either self-propelled or

towed bitumen pressure sprayer with selfheating arrangement and spraying bar with

nozzles having constant volume or pressure system, capable of spraying bitumen atspecified rates and temperature so as to provide a uniformly unbroken spread of bitumen.

Work should be planned so that no more than the necessary tack coat for the days

operation is placed on the surface. After application and prior to succeeding constructionallow the tack coat to cure, without being disturbed, until the water/cutter has completely

evaporated, as determined by the Engineer.

TABLE 500-2. RATE OF APPLICATION OF TACK COAT

Type Surface Quantity of liquid

Bituminous material in kg per 10 sq. m. area

i) Normal bituminous surfaces 2.0 to 2.5

ii) Dry and hungry bituminoussurfaces

2.5 to 3.0

iii) Granular surfaces treated with

primer

2.5 to 3.0

iv) Non bituminous surfacesa) Granular base (not primed)

b) Cement concrete pavement3.5 to 4.0

3.0 to 3.5

Note : There is no need to apply a tack coat on a freshly laid bituminous course if thesubsequent bituminous course is overlaid the same day without opening it to

traffic .

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503.4.Quality Control of Work

Control on the quality of materials and works shall be exercised by the Engineer

in accordance with Section 900.

503.5.Arrangements for Traffic

During the period of construction, the arrangement of traffic shall be done toClause 112.

503.6. Measurement for Payment

Tack coat shall be measured in terms of surface area of application in square

metres.

503.7. Rate

The contract unit rate for tack coat shall be payment in full for carrying out therequired operations including full compensation for all components listed in Clause 401.8

(i) to (v) as applicable to the work specified in these Specifications.

504. BITUMINOUS MACADAM

504.1. Scope

The work shall consist of construction, in a single course, of compacted crushed

aggregates premixed with a bituminous binder, to serve as base/binder course, laidimmediately after mixing, on a base prepared previously in accordance with the

requirement of these Specifications and in conformity with the lines, grades and cross-

sections shown on the drawing or as directed by the Engineer.

504.2. Materials

504.2.1. Bitumen: The bitumen shall be paving bitumen of suitable penetrationgrade (30/40 to 80/100) as per IS : 73. The actual grade of bitumen to be used shall be

decided by the Engineer appropriate to the region, traffic, rainfall and other

environmental conditions. Guidelines on selection of the grade of bitumen are given in

Appendix-4.

504.2.2. Aggregates

504.2.2.1. The aggregates shall consist of crushed stone, crushed gravel/shingle

or other stones. They shall be clean, strong, durable, of fairly cubical shape and free from

disintegrated pieces, organic or other deleterious matter and adherent coating. If crushedshingle/gravel is used, not less than 90 per cent by weight of the gravel/shingle pieces

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retained on 4.75 mm sieve shall have at least two fractured faces. The aggregates shall

preferably be hydrophobic and of low porosity. If hydrophilic aggregates are to be used,the bitumen shall preferably be treated with anti-stripping agents of approved quality in

suitable dose as Appendix-5. The aggregates shall satisfy the physical requirements set

forth in Table 500-3.

TABLE 500-3. PHYSICAL REQUIREMENTS OF AGGREGATES FOR

BITUMINOUS MACADAM

S.No. Test Test Method Requirement

1. Los Angeles Abrasion Value* IS : 2386 (Part-4) 40 per cent Maximum

2. Aggregate Impact Value * IS : 2386 (Part-4) 30 per cent Maximum

3. Flakiness and Elongation

Indices (Total) **

IS : 2386 (Part-1) 30 per cent Maximum

4. Coating and Stripping of

Bitumen Aggregate Mixtures

AASHTO T 182 Minimum retained coating

95 per cent

5. Soundness

(i) Loss with SodiumSulphate 5 cycles

(ii) Loss with Magnesium

Sulphate 5 cycles


18 per cent Maximum

6.Water absorption

IS : 2386 (Part-3) per cent Maximum

* Aggregates may satisfy requirements for either of the two tests.

** To determine this combined proportion, the flaky stone from a representative

sample should first be separated out. Flakiness index is weight of flaky stone

metal divided by weight of stone sample. Only the elongated particles beseparated out from the remaining (non-flaky) stone metal. Elongation index is

weight of elongated particles divided by total non-flaky particles. The value of

flakiness index and elongation index so found are added up.

Note : If crushed slag is used, Clause 404.2.3. shall apply.

504.2.2.2. The aggregate for bituminous macadam shall conform to one of the twogradings in Table 500-4, depending on the compacted thickness; the actual grading shall

be as specified in the Contract.

504.2.3. Proportioning of materials: The bitumen content for premixing shall

be 3 to 3.5 per cent by weight of the total mix except when otherwise directed by the

Engineer.

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TABLE 500-4. AGGREGATE GRADING FOR BITUMINOUS MACADAM

IS Sieve Designation Grading 1 Grading 2

45.0 mm 100 -

26.5 mm 75-100 100

22.4 mm 60-95 75-100

11.2 mm 30-55 50-85

5.6 mm 15-35 20-40

2.8 mm 5-20 5-20

90.0 micron 0-5 0-5

The maximum compacted thickness of a layer shall be 100 mm.

The quantities of aggregates to be used shall be sufficient to yield the specifiedthickness after compaction.

504.2.4. Variation in proportioning of material: The Contractor shall have theresponsibility for ensuring proper proportioning of materials and producing a uniform

mix. A variation in binder content 0.3 per cent by weight of total mix shall, however, be

permissible for individual specimens taken for quality control tests vide Section 900.


504.3.1. Weather and seasonal limitations: The work of laying shall not be

taken up during rainy or foggy weather or when the base course is damp or wet, or during

dust storm or when the atmospheric temperature in shade is 10oC or less.

504.3.2. Preparation of the base: The base on which bituminous macadam is to

be laid shall be prepared, shaped and conditioned to the specified lines, grades and cross-sections in accordance with Clause 501, and a priming coat where needed shall be

applied in accordance with Clause 502 as directed by the Engineer.

504.3.3. Tack coat: A tack coat as per Clause 503 shall be applied over the base.

504.3.4. Preparation and transport of mix: Bituminous macadam mix shall be

prepared in a hot mix plant of adequate capacity and capable of yielding a mix of properand uniform quality with thoroughly coated aggregates.

Hot mix plant shall be of suitable capacity preferably of batch mix type. Totalsystem for crushing of stone aggregates and feeding of aggregate fractions in required

proportions to achieve the desired mix, deployed by the Contractor must be capable of

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meeting the overall Specification requirements under stringent quality control. The plant

shall have the following essential features:

A General

(a) The plant shall have coordinated set of essential units capable of producinguniform mix as per the job mix formula.

(b) Cold aggregate feed system with minimum 4 bins having belt conveyorarrangement for initial proportioning of aggregates from each bin in the required

quantities. In order to have free flow of fines from the bin, it is advisable to have

vibrator fitted on bin to intermittently shake it.

(c) Belt conveyers below each bin should have variable speed drive motors. There

should be electronic load sensor on the main conveyer for measuring the flow ofaggregates.

(d) Dryer unit with burner capable of heating the aggregate to the required

temperature without any visible unburnt fuel or carbon residue on the aggregateand reducing the moisture content of the aggregate to the specified minimum.

(e) The plant shall be fitted with suitable type of thermometric instruments atappropriate places so as to indicate or record/register the temperature of heated

aggregate, bitumen and mix.

(f) Bitumen supply unit capable of heating, measuring/metering and spraying of

bitumen at specified temperature with automatic synchronisation of bitumen and

aggregate feed in the required proportion.

(g) A filler system suitable to receive bagged or bulk supply of filler material and its

incorporation to the mix in the correct quantity wherever required.

(h) A suitable built-in dust control system for the dryer to contain/recycle permissible

fines into the mix. It should be capable of preventing the exhaust of fine dust into

atmosphere for environmental control wherever so specified by the Engineer.

(i) The plant should have centralised control panel/cabin capable of presetting,

controlling/synchronising all operations starting from feeding of cold aggregates

to the discharge of the hot mix to ensure proper quality of mix. It should haveindicators for any malfunctioning in the operation.

(j) Every hot mix plant should be equipped with siren or horn so that the operatormay use the same before starting the plant every time in the interest of safety of

staff.

B - For Batch Type Plant

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(i) Gradation control unit having minimum four deck vibratory screens for accurate

sizing of hot aggregate and storing them in separate bins. This unit should be fullycovered to reduce the maintenance cost and for better environmental condition.

(ii) Proper arrangement for accurate weighing of each size of hot aggregate from the

control panel before mixing.

(iii) Paddle mixer unit shall be capable of producing a homogeneous mix with uniform

coating of all particles of the mineral aggregate with binder.

C - For Continuous Type Plant

(i) Gradation control unit having vibratory screens for accurate sizing of hot

aggregate and storing them in separate bins. This unit should be fully covered to

reduce the maintenance cost and for better environmental condition.

(ii) There should be appropriate arrangement for regulating and volumetric control ofthe flow of hot aggregate from each bin to achieve the required proportioning.

(iii) Paddle mixer unit shall be capable of producing a homogeneous mix with uniform

coating of all particles of the mineral aggregate with binder.

D - For Drum Mix Plant

(i) It is a prerequisite that only properly screened and graded materials are fed to thebins. If required, a vibratory screening unit shall be installed at the plant site to

ensure the same.

A primary 4-deck vibratory screening unit shall be installed before the multiple

bin cold feed system for screening the aggregates and grading the same.

(ii) Belt conveyers below each bin should have variable speed drive motors. Thereshould be electronic load sensor on the main conveyer for measuring the flow of

aggregate.

(iii) There should be arrangement to measure moisture content of the aggregate(s) so

that moisture correction may be applied for working out requirements of binder

and filler.

The temperature of binder at the time of mixing shall be in the range of 150 oC to

163oC and that of the aggregate in the range of 155 oC-163oC. provided that the difference

in temperature between the binder and aggregate at no time exceeds 14oC.

Mixing shall be thorough to ensure that a homogeneous mixture is obtained in

which all particles of the aggregates are coated uniformly, and the discharge temperatureof mix shall be between 130oC to 160 0 C.

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The mixture shall be transported from the mixing plant to the point of use insuitable tipper vehicles. The vehicles employed for transport shall be clean and be

covered in transit if so directed by the Engineer. Any tipper causing excessive

segregation of materials by its spring suspension or other contributing factors or that

which shows undue delay shall be removed from the work unit such conditions arecorrected.

504.3.5. Spreading: The mix transferred from the tipper at site to the paver shallbe spread immediately by means of self-propelled mechanical paver with suitable screeds

capable of spreading, tamping, and finishing the mix true to the specified lines, grades

and cross-sections. The paver finisher shall have the following essential features:

(a) Loading hoppers and suitable distributing mechanism.

(b) All drives having hydrostatic drive/control.

(c) The machine shall have a hydraulically extendable screed for appropriate

width requirement.

(d) The screed shall have tamping and vibrating arrangement for initial

compaction to the layer as it is spread without rutting of otherwise marringthe surface. It shall have adjustable amplitude and variable frequency.

(e) The paver shall be equipment with necessary control mechanism so as toensure that the finished surface is free from surface blemishes.

(f) The paver shall be fitted with an electronic sensing device for automaticlevelling and profile control within the specified tolerances.

(g) The screed shall have the internal heating arrangement.

(h) The paver shall be capable of laying either 2.5 to 4.0 m width or 4.0 to 7.0

m width as stipulated in the Contract.

(i) The paver shall be so designed as to eliminate skidding/slippage of the

tyres during operation.

However, in restricted locations and in narrow widths where the available plantcannot be operated in the opinion of the Engineer, he may permit manual laying of the

mix.

The temperature of the mix at the time of laying shall be in the range of 120 0C to

160 0C. In multi-layer construction, the longitudinal joint in one layer shall offset that in

the layer below by about 150 mm. However, the joint in the top-most layer shall be at thelane line of the pavement.

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Longitudinal joints and edges shall be constructed true to the delineating lineparallel to the centre line of the road . All joints shall be cut vertical to the full thickness

of the previously laid mix and the surface painted with hot bitumen before placing fresh

material. Longitudinal and transverse joints shall be offset by at least 250 mm from those

in the lower courses and the joint on the top-most layer shall not be allowed to fall withinthe wheel path. All transverse joints shall be cut vertically to the full thickness of the

previously laid mix with asphalt cutter/pavement breaker and surface painted with hot

bitumen before placing fresh material. Longitudinal joints shall be preferably hot joints.Cold longitudinal joints shall be properly heated with joint heater to attain a suitable

temperature of about 800C before laying of adjacent material.

504.3.6. Compaction: After the spreading of mix, rolling shall be done by 80 to

100 kN rollers or other approved equipment. Rolling shall start as soon as possible after

the material has been spread deploying a set of rollers as the rolling is to be completed inlimited time frame.

The roller shall move at a speed not more than 5 km/h. Rolling shall be done with

care to avoid unduly roughening of the pavement surface.

Rolling of the longitudinal joints shall be done immediately behind the paving

operation. After this, the rolling shall commence at the edges and progress towards thecentre longitudinally except that on superelevated and uni-directional cambered portions,

it shall progress from the lower to the upper edge parallel to the centre line of the

pavement.

The initial or break-down rolling shall be done with 80-100 kn static weight

smooth wheel roller (3 wheels or tandem), as soon as it is possible to roll the mix withoutcracking the surface or having the mix pick up on the roller wheels. The second or

intermediate rolling shall follow the break-down rolling with vibratory roller of 80 to 100

kN static weight or pneumatic tyred roller of 150 to 250 kN weight, with minimum 7

wheels and minimum tyre pressure of 0.7 MPa as closely as possible to the paver and bedone while the paving mix is still at a temperature that will result in maximum density.

The final rolling shall be done while material is still workable enough for removal of

roller marks, with 6080 kN tandem roller. During the final rolling, vibratory systemshall be switched off. The joints and edges shall be rolled with a 80 to 100 kN static

roller.

When the roller has passed over the whole area once, any high spots ordepressions which become apparent shall be corrected by removing or adding mix

material. The rolling shall then be continued till the entire surface has been rolled to 95

per cent of the average laboratory density (obtained from Marshall specimens compactedas defined in Table 500-10), there is no crushing of aggregates and all roller marks have

been eliminated. Each pass of the roller shall uniformly overlap not less than one-third of

the track made in the preceding pass. The roller wheel shall be kept damp if necessary toavoid bituminous material from sticking to the wheels and being picked up. In no case

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shall fuel, lubricating oil be used for this purpose, nor excessive water poured on the

wheels.

Rolling operations shall be completed in every respect before the temperature of

the mix falls below 100 0 C.

Roller(s) shall not stand on newly laid material while there is a risk that surface

will be deformed thereby. The edges along and transverse of the bituminous macadam

laid and compacted earlier shall be cut to their full depth so as to expose fresh surfacewhich shall be painted with a thin surface coat of appropriate binder before the new mix

is placed against it.

504.4 Surface Finish and Quality Control of Work

The surface finish of construction shall conform to the requirements of Clause902. Control on the quality of materials and works shall be exercised by the Engineer in

accordance with Section 900.

504.5. The bituminous macadam shall be covered with either the next pavementcourse or wearing course, as the case may be, without any delay. If there is to be any

delay, the course shall be covered by a seal coat to the requirement of Clause 513 before

allowing any traffic over it. The seal coat in such cases shall be considered incidental tothe work and shall not be paid for separately.

504.6. Arrangements of Traffic

During the period of construction, arrangement of traffic shall be done to Clause

112.


The work shall be measured as finished work in cubic metres or by weight inmetric tonnes as provided in the Contract.

504.8. Rate

The contract unit rate for the work shall be payment in full for carrying out the

required operations including full compensation for:

(j) Making arrangements for traffic to Clause 112 except for initial treatment

to verge, shoulders and construction of diversions;

(ii) Preparation of base except for laying of profile corrective course but

including filling of potholes;

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(iii) Providing all materials to be incorporated in the work including

arrangement for stock yards, all royalties, fees, rents where necessary andall leads and lifts;

(iv) All labour, tools, equipment, plant including installation of hot mix plant,

power supply units and all machineries, incidental to complete the work tothe Specifications;

(v) Carrying out the work in part widths of the road where directed;

(vi) Carrying out all tests for control of quality; and

(vii) The rate shall cover the provision of bitumen at 3.25 per cent of weight of

total mix, with the provision that the variation of quantity of bitumen will

be assessed and the payment adjusted as per the rate of bitumen quoted.

505. BITUMINOUS PENETRATION MACADAM

505.1. Scope

The work shall consist of construction of one or more layers of compacted

crushed coarse aggregates with alternate applications of bituminous binder and keyaggregates in accordance with the requirements of these Specifications to serve as

base/binder course and in conformity with the lines, grades and cross-sections shown on

the drawings or as directed by the Engineer. Thickness of an individual course shall notexceed 75 mm.

505.2. Materials

505.2.1. Bitumen: The binder shall be paving bitumen of suitable penetration

grade within the range of S-35 to S-90 or A-35 to A-90 (30/40 to 80/100) as per Indian

Standards Specifications for Paving Bitumen IS : 73, or approved cutbacks satisfying

the requirements of IS : 73, 217 or 454. The actual grade of bitumen or cut backs to beused shall be decided by the Engineer, appropriate to the region, traffic, rainfall and other

environmental conditions. Guidance in this regard may be obtained from Appendix-4.

505.2.2. Aggregates

505.2.2.1. The aggregates shall satisfy the physical requirements set forth inClause 504.2.2.1. and Table 500-3.

505.2.2.2. The coarse and key aggregates shall conform to the grading given in

Table 500-5.

505.2.3. Quantities of materials: The quantities of materials used for this work

shall be as specified in Table 500-6.

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505.3.1. Weather and seasonal limitations: Clause No. 504.3.1. shall apply.

505.3.2. Preparation of the base: The base on which the Penetration macadamcourse is to be laid shall be prepared, shaped and conditioned to the specified lines,

grades and sections to Clause 501 or as directed by the Engineer. A priming coat where

needed shall be applied over the base in accordance with Clause 502 or as directed by theEngineer. A tack coat as per Clause 503 shall be applied.

TABLE 500-5. GRADING REQUIREMENTS OF COARSE AGGREGATES

AND KEY AGGREGATES FOR BITUMINOUS

PENETRATION MACADAM

IS Sieve

Designation

Per cent by weight passing the Sieve

For 50mm compacted thickness For 75mm compacted thickness

Coarse Aggregate Key Aggregate Coarse Aggregate Key Aggregate

63 mm - - 100 -

53 mm - - - -

45 mm 100 - 58-82 -

26.5 mm 37-72 - - 100

22.4 mm - 100 5-27 50-75

13.2 mm 2-20 50-75 - -

11.2 mm - - - 5-25

5.6 mm - 5-25 - -

2.8 mm 0-5 0-5 0-5 0-5

TABLE 500-6. QUANTITIES OF MATERIALS REQUIRED FOR 10 sq.m.

OF ROAD SURFACE FOR BITUMINOUS PENETRATION

MACADAM BASE/BINDER COURSE

Compacted

thickness

Binder

Straight run

bitumen

Coarse Aggregate Key Aggregate

50 mm 50kg 0.60 cu.m. 0.15 cu.m.

75 mm 68kg 0.90 cu.m. 0.18 cu.m.

505.3.3.Spreading and compacting coarse aggregates: The coarse aggregate

in a dry and clean form shall be spread uniformly and evenly at the rate specified in Table500-6 preferably with the help of a self-propelled or tipper tail mounted aggregate

spreader capable of spreading aggregate uniformly at the specified rates over the required

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widths. The surface of the layer shall be carefully checked with camber templates and all

high and low spots remedied by removing or adding aggregates as may be required. Thespreading shall be carried no further in advance of the rolling and penetrating operations

than can be completed in one average days work. Segregated aggregates or aggregates

mixed with earth or other foreign substances shall be removed and replaced with graded

aggregates.

505.3.4. Compaction: After the spreading of coarse aggregates, dry rolling shall

be done by 80-100 kN smooth-wheeled steel roller. Rolling shall start as soon as possibleafter the material has been spread. The rolling shall commence at the edges, parallel to

the centre line of the road and progress towards the centre longitudinally except on

superelevated and uni-directional cambered portions, where it shall progress from thelower to the upper edge after the edges have been rolled. For superelevated portions, the

overlapping should be approximately one-third of the width of the rear wheel on each

trip.

After initial dry rolling, the surface shall be checked with a crown template and a3 metre straight-edge. The surface shall not vary more than 10 mm from the template or

straight-edge. All surface irregularities exceeding the above limit shall be corrected byremoving or adding aggregates as required.

The rolling shall be done until the compacted coarse aggregate has firm surfacetrue to the cross section shown on the plans and that it has a texture that will allow free

and uniform penetration of the bituminous material.

505.3.5. Application of bituminous material: After the coarse aggregate has

been rolled and checked, the bituminous binder shall be applied at specified temperatures

as directed by the Engineer. The rate of application shall be as specified in Table 500-6.

At the time of applying the binder, the aggregates shall be surface dry for full

depth of the layer.

The bituminous material shall preferably be applied by a pressure distributor

uniformly over the surface at the specified rate. Over small areas, where the use of a

spray bar is impracticable, the bituminous material shall be applied by the nozzleattachment. Only when permitted, pouring pots may be used according to the directions

of the Engineer.

505.3.6. Application of key aggregates: Immediately after the first penetrationof bitumen, the key aggregates in a clean and dry state shall be spread uniformly over the

surface by means of an approved mechanical spreader or by approved manual methods at

the rate specified in Table 500-6.

If necessary, the surface shall be broomed to ensure uniform application of the

key aggregates. The entire surface shall then be rolled with a 80-100 kN smooth steel

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wheel roller (along with vibratory roller if available) to the Specifications conforming to

Clause 505.3.4.

505.4. Surface Finish and Quality Control

The surface finish of construction shall conform to the requirements of Clause902.

Controls on the quality of materials and works shall be exercised by the Engineerin accordance with Section 900.

505.5. The Penetration Macadam shall be provided with final surfacing(binder/wearing course) without any delay. If there is to be any delay, the course shall be

covered by a seal coat to the requirements of Clause 513 before allowing any traffic over

it. The seal coat in such cases shall be considered incidental to the work and shall not bepaid for separately.

505.6. Arrangements for Traffic

During the period of construction, arrangements for traffic shall be done to Clause

112.


Penetration Macadam Base/Binder Course shall be measured as finished work insquare metres.

505.8. Rate

The contract unit rate for Penetration Macadam Course shall be payment in full

for carrying out the required operations including full compensation for all components

listed in Clause 504.8 (i) to (vi).

506. BUILT-UP SPRAY GROUT

506.1 Scope

This work shall consist of a two-layer composite construction of compacted

crushed coarse aggregates with application of bituminous binder after each layer and keyaggregates on top for the second layer, in accordance with the requirements of these

Specifications to serve as a base course and in conformity with the lines, grades and

cross-sections shown on the drawings or as directed by the Engineer. Thickness of thecourse shall be 75mm.

Built-up spray grout shall be used in a single course in a pavement structure.

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506.2. Materials

506.2.1. Bitumen: Clause 504.2.1 shall apply.

506.2.2. Aggregates: The coarse aggregate shall conform to Clause 504.2.2.1.

The aggregate shall satisfy the physical requirements set out in Table 500-3 .The

coarse and key aggregates for built-up spray grout shall conform to the grading given in

Table 500-7.

TABLE 500-7. GRADING REQUIREMENTS OF COARSE AND KEY

AGGREGATES FOR BUILT-UP SPRAY GROUT

IS Sieve

Designation

Per cent by weight passing the Sieve

Coarse Aggregate Key Aggregate

53.0 mm 100 -

26.5 mm 40-75 -22.4 mm - 100

13.2 mm 0-20 40-75

5.6 mm - 0-20

2.8 mm 0-5 0-5

506 .3. Construction Operations

506.3.1. Weather and seasonal limitations: Clause 504.3.1. shall apply.

506.3.2. Preparation of base: The base on which the built-up spray grout

course is to be laid shall be prepared, shaped and conditioned to the specified lines,grades and cross-sections in accordance with Clause 501. A priming coat where needed

shall be applied in accordance with Clause 502 with suitable primer as directed by the

Engineer.

506.3.3. Tack coat: A tack coat over the base shall be applied as per Clause

503.

506.3.4. Spreading and rolling coarse aggregates for the first layer:Immediately after the application of tack coat, the coarse aggregates in a dry and clean

form shall be spread uniformly and evenly preferably by mechanical means at the rate of

0.5 cu.m. per 10 sq.m area. The surface of the layer shall be carefully checked withtemplates and all high and low spots remedied by removing or adding aggregates as may

be required.

Immediately after spreading of the aggregates, the entire surface shall be rolled

with a 80-100 kN smooth-wheeled roller. Rolling shall commence at the edges andprogress towards the centre except in superelevated and uni-directional cambered

portions where it shall proceed from the lower edge to the higher edge. Each pass of the

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roller shall uniformly overlap not less than one-third of the track made in the preceding

pass.

After initial rolling, the surface shall be checked transversely and longitudinally

with templates and any irregularities corrected by loosening the surface, adding or

removing necessary amounts of aggregate, followed by rolling.

Rolling shall be stopped before voids in the aggregate layer are closed to such an

extent as to prevent free and uniform penetration of the binder.

506.3.5. Application of binder-first spray: The binder shall be heated to the

temperature appropriate to grade of bitumen approved by the Engineer and sprayed onaggregate layer at the rate of 15 kg/10 sq. m. (in terms of straight-run bitumen) in a

uniform manner with the help of mechanical sprayers capable of spraying bitumen

uniformly at specified rates and temperatures. Excessive deposits of binder caused bystopping or starting of the sprayers or through leakage or any other reason shall be

corrected promptly.

506.3.6. Spreading and rolling of coarse aggregate for the second layer:Immediately after the first application of the binder, the second layer of coarse aggregates

shall be spread and rolled to Clause 506.3.4.

506.3.7. Application of binder-second spray: The second aggregate layer shall

then be given a binder spray at the rate of 15 kg/10 sq.m. (in terms of straight-run

bitumen) to Clause 506.3.5.

506.3.8. Application of key aggregate: Immediately after second application of

the binder, key aggregates in a clean and dry state shall be spread uniformly and evenly,preferably by mechanical means at the rate of 0.13 cu.m./10 sq.m. so as to cover the

surface completely. If necessary, the surface shall be broomed to ensure uniform

application of the key aggregates. The entire surface shall then be rolled with a 80-100

kN smooth-wheeled roller to Clause 506.3.4. While rolling is in progress, additional keyaggregates, where required, shall be spread by hand. Rolling shall continue until the

entire course is thoroughly compacted and key aggregates are firmly in position.

506.4. Surface Finish and Quality Control

The surface finish of construction shall conform to the requirements of Clause

902.



506.5. The built-up-spray-grout shall be provided with final surfacing without any

delay. If there is to be any delay, the course shall be covered by a seal coat to the

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requirement of Clause 513 before allowing any traffic over it. The seal coat in such cases

shall be considered incidental to the work and shall not be paid for separately.


During the period of construction, arrangement of traffic shall be done to Clause112.


Built-up spray grout shall be measured as finished work in square metres.

506.8. Rate

The contract unit rate for built-up spray grout shall be payment in full for carryingout the required operations including full compensation for all components listed in

Clause 504.8 (i) to (vi).

507. DENSE BITUMINOUS MACADAM

507.1. Scope

This work shall consist of construction in a single course of 50 to 100 mm thick

base/binder course to the following Specifications on a previously prepared base.

507.2. Materials

507.2.1. Bitumen: The bitumen shall be paving bitumen of Penetration Grade S65 or A 65 (60/70) as per Indian Standard Specifications for Paving Bitumen IS : 73.

In case of non-availability of bitumen of this grade, S 90 (80/100) grade bitumen may be

used with the approval of the Engineer. Guidance to selection of the grade of bitumen

may be taken from Appendix-4.

507.2.2. Coarse aggregates: The coarse aggregates shall consist of crushed

stone, crushed gravel/shingle or other stones. They shall be clean, strong, durable, offairly cubical shape and free from disintegrated pieces, organic or other deleterious

matter and adherent coating. The aggregates shall preferably be hydrophobic and of low

porosity. If hydrophilic aggregates are to be used, the bitumen shall be treated with

antistripping agents of approved quality in suitable doses. The aggregates shall satisfy thephysical requirements set forth in Table 500-8.

If crushed gravel/shingle is used, not less than 90 per cent by weight of thegravel/shingle pieces retained on 4.75 mm sieve shall have at least two fractured faces.

The portion of the total aggregate passing 4.75mm sieve shall have a sand equivalent

value of not less than 50 when tested in accordance with the requirement of IS : 2720(Part-37).

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The plasticity index of the fraction passing the 425 micron sieve shall not exceed4.

TABLE 500.8. PHYSICAL REQUIREMENTS OF AGGREGATES FOR DENSE

BITUMINOUS MACADAMS.No. Test Test Method Requirement

1. Los Angles Abrasion * Value IS : 2386 (Part-4) 40 per cent Maximum

2. Aggregate Impact value * IS : 2386 (Part-4) 30 per cent Maximum3. Flakiness and Elongation**

Indices (Total)


4. Coating and Stripping of BitumenAggregate Mixtures

AASHTO T 182 Minimum retainedcoating 95 per cent

5. Soundness

(i) Loss with Sodium Sulphate(ii) Loss of Magnesium Sulphate

IS : 2386 (Part-5)

5 cycles5 cycles

12 per cent Maximum18 per cent Maximum

6. Water absorption IS : 2386 (Part-3) 2 per cent Maximum

* Aggregates may satisfy requirements of either of the two tests.

** To determine this combined proportion, the flaky stone from a representative sample

should first be separated out. Flakiness index is weight of flaky stone metal divided

by weight of stone sample. Only the elongated particles be separated out from theremaining (non-flaky) stone metal. Elongation index is weight of elongated particles

divided by total non-flaky particles. The value of flakiness index and elongation

index so found are added up.

507.2.3. Fine aggregates: Fine aggregates shall be the fraction passing 2.36 mm

sieve and retained on 75 micron sieve, consisting of crusher-run screening , gravel , sandor a mixture of both. These shall be clean, hard, durable, uncoated, dry and free from any

injurious, soft or flaky pieces and organic or other deleterious substances.

507.2.4. Filler: Filler shall consist of finely divided mineral matter such as rockdust, hydrated lime or cement as approved by the Engineer.

The filler shall be graded within the following limits:

IS Sieve Per cent passing by weight

600 Micron 100

300 Micron 95 - 10075 Micron 85 100

The filler shall be free from organic impurities and have a Plasticity Index notgreater than 4. The Plasticity Index requirement shall not apply if filter is cement or lime.

When the coarse aggregate is gravel, 2 per cent by mass of total aggregate of portland

cement or hydrated lime shall be added and the percentage of fine aggregate reduced

accordingly. Cement or hydrated lime is not required when the gravel is limestone.

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507.2.5. Aggregate gradation: The combined coarse and fine aggregates andfiller (when used) shall produce a mixture to conform to the grading set forth in Table

500-9.

Table 500-9. AGGREGATE GRADATION FOR DENSE BITUMINOUSMACADAM

Sieve Designation Percentage passing the sieve by weight

37.5 mm 10026.5 mm 90-100

13.2 mm 56-80

4.75 mm 29-592.36 mm 19-45

300 micron 5-17

75 micron 1-7

The aggregate mix, as used in work, shall not vary from the low limit on one sieve to the

high limit on the adjacent sieve but shall be well graded.

507.3. Mix Design

507.3.1. Requirement of mix: Apart from conformity with grading and quality

requirements of individual ingredients, the mix shall meet the requirements set out in

Table 50010.

Table 500-10. REQUIREMENTS OF DENSE BITUMINOUS MACADAM MIX

S. No. Description Requirements

1. Marshall stability (ASTM Designation-D-1559) 820 kg (1800 lb)

determined on Marshall specimens compacted minimumby 75 compaction blows on each end

2. Marshall flow (mm) 2-4

3. Per cent Air voids 3-5

4. Minimum voids in mineral aggregates (VMA) 10 per cent-12 per cent5. Per cent voids in mineral aggregates filled

by bitumen (VFB) 65-756. Binder content per cent by weight of total mix Not less than 4.0 per cent

507.3.2. Binder content: The binder content shall be so fixed as to achieve the

requirements of the mix set out in Table 500-10. Marshall method for arriving at the

binder content shall be adopted, replacing the aggregates retained on 26.5 mm sieve bythe aggregates passing 26.5 mm sieve and retained on 22.4 mm sieve.

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507.3.3. Job mix formula: The Contractor shall intimate to the Engineer inwriting, atleast 20 days before the start of the work, the job mix formula proposed to be

used by him for the work and shall give the following details:

i) Source and location of all materials;

ii) Proportions of all materials expressed as follows where each is applicable;

(a) Binder, as percentage by weight of total mix;

(b) Coarse aggregate/Fine aggregate/Mineral filler as percentage byweight of total aggregate including mineral filler;

iii) A single definite percentage passing each sieve for the mixed aggregate;

iv) The results of tests enumerated in Table 500-10 as obtained by the Contractor;

v) Test results of physical characteristics of aggregates to be used;

vi) Mixing temperature and compacting temperature.

While working out the job mix formula, the Contractor shall ensure that it is

based on a correct and truly representative sample of the materials that will actually be

used in the work and that the mix and its different ingredients satisfy the physical andstrength requirements of these Specifications.

Approval of the job mix formula shall be based on independent testing by theEngineer for which samples of all ingredients of the mix shall be furnished by the

Contractor as required by the former.

The approved job mix formula shall remain effective unless and until modified bythe Engineer. Should a change in the source of materials be proposed, a new job mix

formula shall be established and got approved from the Engineer before actually using

the materials.

507.3.4. Permissible variation from job mix formula: It shall be the

responsibility of the Contractor to produce a uniform mix conforming to the approved job

mix formula subject to the permissible variations of the individual percentages of thevarious ingredients in the actual mix from the job mix formula to be used within the

limits as specified in Table 500-11. These variations are intended to apply to individual

specimens taken for quality control tests vide Section 900.

TABLE 500-11. PERMISSIBLE VARIATIONS FROM THE JOB MIX

FORMULA

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S. No. Description of Ingredients Permissible variation

by weight of total

mix-in per cent

1. Aggregate passing 13.2 mm sieve and larger sieves + 82. Aggregate passing 11.2 mm sieve and 5.6 mm sieve + 7

3. Aggregate passing 2.80 mm sieve and 1.40 mm sieve + 6

4. Aggregate passing 710 micron sieve and 355 micron sieve + 55. Aggregate passing 180 micron sieve + 4

6. Aggregate passing 90 micron sieve + 2

7. Binder + 0.38. Mixing temperature + 10oC


507.4.1. Weather and seasonal limitations: Clause 504.3.1. shall apply.

507.4.2. Preparation of base: The base on which Dense Bituminous Macadam

is to be laid shall be prepared, shaped and conditioned to the specified lines, grades and

cross sections in accordance with Clause 501 or as directed by the Engineer . The surfaceshall be thoroughly swept clean free from dust and foreign matter using mechanical

broom and dust removed or blown off by compressed air. In portions where mechanical

means cannot reach, other approved method shall be used. A priming coat where needed,shall be applied in accordance with Clause 502 or as directed by the Engineer.

507.4.3. Tack coat : A tack coat over the base shall be applied as per Clause 503.

507.4.4. Preparation of mix: Clause 504.3.4. shall apply.

507.4.5. Spreading: The mix transported from the hot mix plant to the site shallbe spread by means of a self-propelled paver with suitable screeds capable of spreading,

tamping and finishing the mix to specified grade, lines and cross-section. Paver Finisher

shall have the essential features as spelt out in Clause 504.3.5. However, in restrictedlocations and in narrow widths where the available equipment cannot be operated in the

opinion of the Engineer, he may permit manual laying of the mix. Similarly for smaller

jobs, mechanical paver may be used with the approval of the Engineer.

The temperature of mix at the time of laying shall be in the range of 1200-160 0 C.

Mixes with a temperature of less than 120 0 C shall not be put into paver spreader.Longitudinal joints and edges shall be constructed true to the delineating lines parallel to

the centre line of the road. Longitudinal and transverse joints shall be offset by at least

250 mm from those in the lower courses and the joint on the top most layer shall not beallowed to fall within the wheel path. All transverse joints shall be cut vertically to the

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full thickness of the previously laid mix with asphalt cutter and the surface painted with

hot bitumen before placing fresh material. Longitudinal joints shall be preferably hotjoints. Cold longitudinal joints shall be properly heated with joint heater to attain a

suitable temperature of about 80 0 C laying of adjacent material.

507.4.6. Rolling: After spreading the mix by paver, it shall be thoroughlycompacted by rolling with a set of rollers moving at a speed not more than 5 km/h,

immediately following close to the paver. Generally the initial or breakdown rolling shall

be done with 80-100 kN static weight smooth-wheeled roller. The intermediate rollingshall be done with 80-100 kN static weight vibratory roller or with a pneumatic tyred

roller of 150-250 kN weight having a tyre pressure of at least 0.7 MPa. The finish rolling

shall be done with 60-80 kN weight smooth wheeled tandem roller. All the compactionoperations, i.e., breakdown rolling and intermediate rolling can be accomplished by using

vibratory tandem roller of 80-100 kN static weight. During initial breakdown rolling and

finish rolling, no vibratory compaction shall be resorted to. The exact pattern of rollingshall be established after trial compaction as approved by the Engineer. Any

displacement occurring as a result of reversing of the direction of a roller or from anyother cause shall be corrected at once as specified and/or removed and made good. The

rollers shall not be permitted to stand on pavement which has not been fully compactedand where temperature is still more than 70oC. Necessary precautions shall be taken to

prevent dropping of oil, grease, petrol or other foreign matter on the pavement either

when the rollers are operating or standing.

The wheels of roller shall be kept moist to prevent the mix from adhering to them.

But in no case shall fuel/lubricating oil be used for this purpose nor excessive waterpoured on the wheels. Rolling shall commence longitudinally from edges and proceed

towards the centre, except that on superelevated and unidirectional cambered portions, it

shall progress from the lower to upper edge parallel to the centre line of the pavement.The roller shall proceed on the fresh material with rear or fixed wheel leading so as to

minimise the pushing of the mix and each pass of the roller shall overlap the preceding

one by half the width of the rear wheel.

Rolling shall be continued till the density achieved is at least 98 per cent of that of

laboratory Marshall specimen (compacted as defined in Table 500-10) and all roller

marks are eliminated. Skin patching of an area that has been rolled will not be permitted.Rolling operations shall be completed in all respects before the temperature of the mix

falls below 1000C.

507.5. Opening to Traffic

Traffic may be allowed after completion of the final rolling when the mix has

cooled down to the surrounding temperature. The Dense Bituminous Macadam shall be

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provided with an appropriate wearing course as early as possible prior to regular opening

to normal traffic and/or impending rain.

507.6. Surface Finish and Quality Control of Work

The surface finish of construction shall conform to the requirements of Clause902.

Control on the quality of materials and work shall be exercised by the Engineer inaccordance with Section 900.


During the period of construction, arrangements for the traffic shall be done to

Clause 112.


Dense Bituminous Macadam shall be measured as finished work in cubic metresor tonnes as directed by the Engineer.

507.9. Rate

The contract unit rate for Dense Bituminous Macadam shall be payment in full for

carrying out the required operations including full compensation for all components listedin Clause 504.8 (i) to (vi). The rate shall cover the provision of bitumen in the mix at 4.5

per cent of the weight of the total mix, with the provision that the variation of quantity of

bitumen will be assessed and the payment adjusted as per the rate of bitumen quoted.

508. SURFACE DRESSING

508.1. Single and Two-Coat Surface Dressing using Bitumen

508.1.1. Description: This work shall consist of the application of one coat or

two coats of surface dressing, each coat consisting of a layer of bituminous bindersprayed on base prepared previously, followed by a cover of stone chippings properly

rolled to form a wearing course to the requirements of these Specifications.

508.1.2. Materials

508.1.2.1 Binder: The binder shall be straight-run bitumen of a suitable grade

appropriate to the region, traffic, rainfall and other environmental conditions as directedby the Engineer and conforming to IS : 73. Guidance in this regard may be obtained

from Appendix-4.

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508.1.2.2. Stone chippings: The stone chippings shall conform to Clause

504.2.2.1. The Stone Polishing Value as measured by BS 812 (Part 114), shall not beless than 55. The stone chippings shall also conform to the quality requirements of Table

500-3 except that water absorption shall be restricted to a maximum of 1 per cent. The

size of stone chippings shall be in accordance with Table 500-12.

508.1.2.3. Quantities of materials: The quantities of materials used for this work

shall be as specified in a Table 500-13.

TABLE 500-12. SIZE REQUIREMENTS OF STONE CHIPPINGS FOR

SURFACE DRESSING USING BITUMEN

S.

No.

Type of construction Normal size of

stone chippings

Specifications

1. Single coat surface dressing

or the first coat of two-coatsurface dressing

13.2 mm 100 per cent passing through

22.4 mm sieve & retained on11.2 mm sieve.

2. Second coat of two-coat

surface dressing (also used as

a renewal coat)

11.2 mm 100 per cent passing through

13.2 mm sieve & retained on

5.6 mm sieve.

TABLE 500-13. QUANTITIES OF MATERIALS REQUIRED FOR 10 sq. m. OF

ROAD SURFACE FOR SURFACE DRESSING USING

BITUMEN

S. No. Type of construction Binder Stone chippings

1. Single coat surface dressing or thefirst coat of the two-coat surface

dressing

18.0 kg 0.15 cu.m

2. Second coat of the two-coat surface

dressing (also used as a renewal coat)

10.0 kg 0.10 cu.m

508.1.3. Construction operations

508.1.3.1. Weather and seasonal limitations: Clause 504.3.1. shall apply.

508.1.3.2. Preparation of base: The base on which the surface dressing is to be

laid shall be prepared, shaped and conditioned to the specified lines, grade and cross-section in accordance with Clause 501 and as directed by the Engineer. Priming coat,

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where needed, shall be provided as per Clause 502 and as directed by the Engineer.

Where the existing surface shows signs of fatting up, this shall be rectified. Thebituminous primed surface to be dressed shall be thoroughly cleaned either by using a

mechanical broom or any other approved equipment/method as specified by the Engineer.

Dust removed in the process shall be blown off with the help of compressed air.

508.1.3.3. Application of binder: Bitumen shall be heated to 150oC-163oC and

sprayed on the dry surface in a uniform manner with the help of self-propelledmechanical sprayers having self-heating arrangement and bitumen pressure pump and

spraying bar with nozzles having constant volume or pressure system capable of spraying

bitumen uniformly at the rates specified in Table 500-13 and above mentionedtemperature. Excessive deposits of binder caused by stopping or starting of the sprayer or

through leakages or any other reason shall be corrected by blotting with sand before the

stone chippings are spread.

508.1.3.4. Application of stone chippings: Immediately after the application ofbinder, stone chippings in a dry and clean state shall be spread uniformly on the surface

by means of a self-propelled or towed mechanical grit spreader capable of sprayinguniformly at rates specified in Table 500-13 so as to cover the surface completely. If

necessary, the surface shall be broomed to ensure uniform spread of chippings.

508.1.3.5. Rolling: Immediately after the application of the cover material, the

entire surface shall be rolled with a 80-100 kN smooth wheeled steel roller, 80-100 kN

static weight vibratory roller, or other approved equipment. Rolling shall commence atthe edges and progress towards the centre except in superelevated and uni-directional

cambered portions where it shall proceed from the lower edge to the higher edge. Each

pass of the roller shall uniformly overlap not less than one-third of the track made in thepreceding pass. While rolling is in progress, additional chippings shall be spread by hand

in necessary quantities required to make up irregularities. Rolling shall continue until all

aggregate particles are firmly embedded in the binder and present a uniform closed

surface.

508.1.3.6. Application of second coat of surface dressing: Where surface

dressing in two coats is specified, the second coat shall be applied immediately afterlaying of the first coat. The construction operations for the second coat shall be the same

as described in Clause 508.1.3.3. to 508.1.3.5.

508.1.4. Opening to traffic: Traffic shall not be permitted to run on any newlysurface dressed area until the following day. In special circumstances, however, the

Engineer may open the road to traffic immediately after rolling, but in such cases traffic

speed shall be limited to 16 km per hour till the following day.

508.1.5. Surface finish and quality control of work: The surface finish of

construction shall conform to the requirements of Clause 902.

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508.1.6. Arrangements for traffic: During the period of construction,

arrangement of traffic shall be done as per Clause 112.

508.1.7. Measurements for payment: Each coat of surface dressing shall be

measured as finished work in square metres.

508.1.8. Rates: The contract unit rate for each coat of surface dressing shall be

payment in full for carrying out the required operations including full compensation for

all components listed in Clause 504.8 (i) to (vi).

508.2. Two-Coat Surface Dressing Using Cationic Bitumen Emulsion

508.2.1. Scope

508.2.1.1. This work shall consist of two-coat surface dressing, each coat

consisting of a layer of cationic bitumen emulsion binder sprayed on a base preparedpreviously, followed by a cover of stone aggregate, properly rolled to form a wearing

course to the requirements of these Specifications.

508.2.1.2. It shall, however, not be applicable to a single coat surface dressing

using cationic bitumen emulsion.

508.2.2. Material

508.2.2.1. Binder: The binder shall be a Cationic type bitumen emulsion ofRapid Setting (RS) grade complying with IS : 8887 and having bitumen content 60 per

cent minimum by weight.

508.2.2.2. Aggregates

(A) General Requirements: Clause 508.1.2.2. shall apply

except the size requirement which shall be as given in Table 500-14. Wetaggregates can be used for surface dressing with Cationic bitumen

emulsions and when aggregates are dusty, they should be cleaned by

washing or by sprinkling water copiously. If the road surface is dry, a light

sprinkling with water shall be done.

(B) Size: The aggregates shall conform to the size given in Table 500-14.

TABLE 500-14. REQUIREMENTS OF STONE CHIPPINGS FOR SURFACE

DRESSING USING BITUMEN EMULSION

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1. For first coat-13.2 mm size Passing 22.4 mm sieve and retained on 11.2 mm

sieve.

2. For second coat-6.7 mm size Passing 9.5 mm sieve and retained on 2.36 mm sieve.

(C) Quantities of materials: The quantities of materials used for thiswork shall be as given in Table 500-15.

TABLE 500-15. REQUIREMENTS OF MATERIALS USING BITUMEN

EMULSION

Material For 10 sq.m. area For First Coat For Second Coat

Cationic Bitumen Emulsion 12 to 14 kg 16 to 18 kg

Aggregates 0.10 to 0.12 cu. m. 0.06 to 0.08 cu. m.


508.2.3.1. Weather limitations: Cationic bitumen emulsions should not

normally be stored below 0oC. However, surface dressing with Cationic bitumen

emulsion should be carried out only when the atmospheric temperature is above 10 oC.The work can be carried out when the base is damp. All standing water in depressions

shall, however, be removed.

508.2.3.2. Preparation of base: The existing base on which surface dressing isto be laid shall be prepared, shaped and corrected to a uniform grade and camber in

accordance with Clause 501.

The surface shall be cleaned to remove all loose particles, dust and foreign matter.

It is preferable to spray water on the surface to settle the loose dust and also to expose

clean surface of aggregates in the case of granular base courses.

508.2.3.3. Preparation of binder: Before opening, the Cationic bitumen

emulsion drums should be rolled at slow speed, to and fro, for a distance of about 10

metres, 5 to 6 times to mix the contents properly.

508.2.3.4. First Coat

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(A) Application of Binder: :Cationic bitumen emulsion binder can be applied

on wet road surface. If the road surface is dry, light sprinkling with watershall be done. Cationic bitumen emulsion shall be sprayed uniformly on the

prepared base by mechanical sprayers. In exceptional cases spraying from a

spraying can may be resorted to as directed by the Engineer. The spraying

can should have 6mm diameter holes spaced 30 mm apart to preventclogging. An emulsion tank of 30 litres capacity pressurized by compressed

air from a hand pump and a 12 mm flexible pipe with a spray nozzle is a

simple and efficient arrangement for spraying.

(B) Application of aggregate: Immediately after spraying of

Cationic emulsion, aggregate of 13.2 mm size shall be spread uniformly andevenly by mechanical means to cover the surface completely and evenly.

Any oversize aggregate, if seen, shall be removed.

(C ) Rolling: Immediately after the application of cover

material, the surface shall be rolled with 80-100 kN roller preferably bysmooth wheeled tandem type. The rolling shall begin at the edge and

proceed towards the centre, parallel to the centre line except insuperelevated and unidirectional cambered portions where it shall proceed

from the lower edge to the higher edge. While rolling, aggregates shall be

added or removed so as to ensure a uniformly covered surface. Each-pass ofroller shall uniformly overlap not less than one third of the track made in the

preceding pass. Rolling shall continue for just enough time to embed the

aggregates in the binder and present a uniform closed surface. Excessiverolling, resulting in crushing of aggregates shall be avoided.

508.2.3.5. Second coat

(A) Time interval: The second coat of surface dressing shall

be applied on the same day as the first coat but at least not earlier than one

hour after finishing the rolling of the first coat.

(B) Application of emulsion: Traffic shall not be allowed on the first

coat before the application of second coat. If the aggregates of the first coatappear to be loose and unbounded in few spots, the same shall not be

disturbed.

The Cationic bitumen emulsion for second coat shall be sprayed bymechanical sprayer or in exceptional cases by using pouring can with the

approval of the Engineer, taking care not to disturb the first layer while

walking over it.

(C ) Application of aggregate: Immediately after the

application of emulsion, 6.7 mm size aggregates shall be spread uniformlyby mechanical means to cover the whole surface evenly.

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(D) Rolling: Rolling shall start soon after spreading theaggregates and all operations carried out as per Clause 508.2.3.4 (C) to

achieve a uniform closed surface.

(E) Finishing: After one pass of the roller, depressions shall be filled with 6.7mm size aggregate. If excess of aggregate is found in isolated spots, the

bigger size aggregates shall be removed to give a uniform surface. Finish

rolling on the next day helps to give a firm surface.

508.2.4. Opening to traffic: The road may be opened to traffic 4 hours after

completing rolling of the second coat, but preferably the next day after 24 hours.

Where the road width is single lane, traffic can be allowed at slow speed of not

more than 10 km per hour making sure to add aggregates and emulsion wherever thesurface has been picked up by traffic.

508.2.5. Surface finish and quality control of work: The surface finish of

construction shall conform to the requirements of Clause 902.



508.2.6. Arrangement for traffic: During the period of construction,

arrangement of traffic shall be done to Clause 112.

508.2.7. Measurements for payment: Two coats of surface dressing shall be

measured as a finished work in square metres.

508.2.8. Rate: The contract unit rate for two coats of surface dressing shall be

payment in full for carrying out the required operations including full compensation for

all components listed in Clause 504.8 (i) to (vi).

508.3. Surface Dressing with Precoated Aggregate using Bitumen

508.3.1. Scope

508.3.1.1. The work shall consist of application of either a single coat or two

coats of surface dressing over a previously prepared base, each coat consisting ofapplication of bituminous binder sprayed on a base previously prepared followed by a

cover of precoated materials properly rolled to form a wearing course to the requirements

of these Specifications.

508.3.1.2. This Specification may be adopted in lieu of the conventional surface

dressing to Clause 508.1, in situations where better adhesion is required between theaggregates and binder during construction and later in service. The technique is basically

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the same as conventional surface dressing except that a small quantity of binder is used

for precoating the aggregates. However, it is quite different from premix construction.

508.3.2. Materials

508.3.2.1. Binder: The binder shall be straight run bitumen of a suitable gradeappropriate to the region, traffic and other environmental conditions and as directed by

the Engineer and conforming to IS : 73.

508.3.2.2. Aggregates: The aggregates shall conform to Clause 504.2.2. They

shall conform to the quality requirements of Table 500-3 except that the water absorption

shall be restricted to maximum of 1 per cent. The Stone Polishing Value as measured byBS : 812 (Part-114) shall not be less than 55.

The size of the aggregates shall be in accordance with Table 500-12.

508.3.2.3. Quantities of materials: The quantities of materials used for thiswork shall be as specified in Table 500-12 and 500-13.

508.3.2.4. Precoating: The aggregates shall be precoated with 0.75 to 1.00 per

cent of their weight with binder and shall not be precoated simultaneously with the

surface dressing operation. The precoated aggregates shall be allowed to cure for at leastone week so that they become non-sticky to facilitate easy spreading like normal

uncoated aggregates. The aggregates, free of dust or fine particles shall be preheated to

160oC for precoating and then mixed with bitumen binder (0.75 to 1.00 per cent byweight of aggregate) heated to its application temperature. The aggregates and binder

shall be thoroughly mixed in a mixer of approved type till the aggregates are uniformly

coated.


508.3.3.1. Weather and seasonal Limitations: Clause 504.3.1 shall apply.

508.3.3.2. Preparation of base: Clause 508.1.3.2 shall apply.

508.3.3.3. Application of binder: After deducting the binder quantity consumed

in precoating aggregates for first coat in terms of para 508.3.2.4. from the quantities

specified in Table 500-13, remaining binder of first coat shall be heated to 1500 C165 0C

and sprayed on the clean and dry surface in a uniform manner prefe

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